Method of fabricating a semiconductor device

ABSTRACT

A method for fabricating a semiconductor device includes forming a gate electrode structure over a first region of a semiconductor substrate, and selectively forming an oxide layer overlying the gate electrode structure by reacting a halide compound with oxygen to increase a height of the gate electrode structure. The halide compound may be silicon tetrachloride, and the oxide layer may be silicon dioxide. The gate electrode structure may be a dummy gate electrode, which is subsequently removed, and replaced with another gate electrode structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application62/434,814 filed Dec. 15, 2016, the entire disclosure of which isincorporated herein by reference.

TECHNICAL FIELD

This disclosure is directed to a method of increasing the height of alevel of various elements of a semiconductor device during semiconductordevice processing.

BACKGROUND

As the semiconductor industry has progressed into nanometer technologyprocess nodes in pursuit of higher device density, higher performance,and lower costs, challenges from both fabrication and design issues haveresulted. In particular, increasing device density has produced veryhigh gate heights and gate aspect ratio. High gate height and aspectratio tends to lead to gate incline or collapse. In addition, as moresteps are performed on semiconductor devices to increase device density,gate electrodes are exposed to an increasing number of process stepsthat can degrade the gate electrode and cause gate electrode height toshrink. If the gate height is too short the device can be damaged duringthe formation of overlying layers. A method of maintaining proper gateheight throughout the semiconductor processing operations is desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 is a plan view of a semiconductor device according to anembodiment of the present disclosure.

FIG. 2 shows one stage of a sequential process for manufacturing asemiconductor device according to an embodiment of the presentdisclosure.

FIG. 3 shows a cross-sectional view taken along line A-A of FIG. 1 ofone stage of a sequential process performed on the device of FIG. 2 formanufacturing a semiconductor device according to an embodiment of thepresent disclosure.

FIG. 4 shows one stage of a sequential process performed on the deviceof FIG. 3 for manufacturing a semiconductor device according to anembodiment of the present disclosure.

FIG. 5 shows one stage of a sequential process performed on the deviceof FIG. 4 for manufacturing a semiconductor device according to anembodiment of the present disclosure.

FIG. 6 shows a cross-sectional view taken along line B-B of FIG. 1 ofone stage of a sequential process performed on the device of FIG. 5 formanufacturing a semiconductor device according to an embodiment of thepresent disclosure.

FIG. 7 shows one stage of a sequential process performed on thesemiconductor device of FIG. 6 according to an embodiment of the presentdisclosure.

FIG. 8 shows one stage of a sequential process performed on the deviceof FIG. 7 for manufacturing a semiconductor device according to anembodiment of the present disclosure.

FIG. 9 shows one stage of a cross-sectional view taken along line A-A ofFIG. 1 of the semiconductor device of FIG. 8 according to an embodimentof the present disclosure.

FIG. 10 shows one stage of a cross-sectional view taken along line B-Bof FIG. 1 of a sequential process for manufacturing a semiconductordevice performed on the device of FIG. 8 according to an embodiment ofthe present disclosure.

FIG. 11 shows one stage of a sequential process performed on the deviceof FIG. 10 for manufacturing a semiconductor device according to anembodiment of the present disclosure.

FIG. 12 shows one stage of a sequential process performed on the deviceof FIG. 11 for manufacturing a semiconductor device according to anotherembodiment of the present disclosure.

FIG. 13 shows one stage of a sequential process performed on the deviceFIG. 12 for manufacturing a semiconductor device according to anembodiment of the present disclosure.

FIG. 14 shows one stage of a sequential process performed on the deviceof FIG. 13 for manufacturing a semiconductor device according to anembodiment of the present disclosure.

FIG. 15 shows one stage of a sequential process performed on the deviceof FIG. 14 for manufacturing a semiconductor device according to anembodiment of the present disclosure.

FIG. 16 shows one stage of a sequential process performed on the deviceof FIG. 14 for manufacturing a semiconductor device according to anembodiment of the present disclosure.

FIG. 17 shows one stage of a sequential process performed on the deviceof FIG. 16 for manufacturing a semiconductor device according to anembodiment of the present disclosure.

FIG. 18 shows one stage of a sequential process performed on the deviceof FIG. 17 for manufacturing a semiconductor device according to anotherembodiment of the present disclosure.

FIG. 19 shows one stage of a sequential process performed on the deviceof FIG. 18 for manufacturing a semiconductor device according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the invention. Specific embodiments or examples of components andarrangements are described below to simplify the present disclosure.These are, of course, merely examples and are not intended to belimiting. For example, dimensions of elements are not limited to thedisclosed range or values, but may depend upon process conditions and/ordesired properties of the device. Moreover, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed interposing the first and second features, suchthat the first and second features may not be in direct contact. Variousfeatures may be arbitrarily drawn in different scales for simplicity andclarity.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The device may be otherwise oriented (rotated 90 degrees orat other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“made of” may mean either “comprising” or “consisting of.”

To prevent damage to a semiconductor device during semiconductor devicefabrication processes, it is important to maintain a proper height ofeach level of various components of the semiconductor device. Levelheight can decrease due to semiconductor processing steps, includingvarious etching operations. To counteract level height shrinkage, theheight of the gate electrodes or interlayer dielectric layers isincreased during semiconductor processing according to some embodimentsof the present disclosure.

FIG. 1 is a plan view of an embodiment of a semiconductor deviceaccording to the present disclosure.

FIGS. 2-11 show exemplary sequential processes for manufacturingsemiconductor devices according to embodiments of the presentdisclosure. It is understood that additional operations can be providedbefore, during, and after processes shown by FIGS. 2-11, and some of theoperations described below can be replaced or eliminated, for certainembodiments of the method. The order of the operations/processes may beinterchangeable.

A plan view of a semiconductor device is illustrated in FIG. 1. As shownin FIG. 1, a plurality of gate electrode structures 65 are formedoverlying a plurality of fin structures 15. Although three finstructures and three gate electrode structures are shown, methods anddevices according to the present disclosure may include one, two, four,or more fin structures and one, two, four, or more gate electrodestructures.

In some embodiments of the present disclosure, a semiconductor substrate10 is provided. The substrate 10 includes a single crystallinesemiconductor layer on at least its surface portion. The substrate 10may comprise a single crystalline semiconductor material such as, butnot limited to Si, Ge, SiGe, GaAs, InSb, GaP, GaSb, InAlAs, InGaAs,GaSbP, GaAsSb, InP, or any combination thereof. In a certain embodiment,the substrate 10 is made of Si.

The semiconductor substrate 10 is patterned in some embodiments to forma plurality of fin structures 15, as shown in FIG. 3. The semiconductorsubstrate 10 is patterned by photolithographic and etching operations insome embodiments. In other embodiments, fin structures 15 are formed onthe substrate 10 by semiconductor material deposition operations. Asshown in FIG. 1, the fin structures 15 extend in a first direction(e.g., Y direction) and the plurality of fin structures 15 are arrangedalong a second direction (e.g., X direction) substantially perpendicularto the first direction.

The fins may be patterned by any suitable method. For example, the finsmay be patterned using one or more photolithography processes, includingdouble-patterning or multi-patterning processes. Generally,double-patterning or multi-patterning processes combine photolithographyand self-aligned processes, allowing patterns to be created that have,for example, pitches smaller than what is otherwise obtainable using asingle, direct photolithography process. For example, in one embodiment,a sacrificial layer is formed over a substrate and patterned using aphotolithography process. Spacers are formed alongside the patternedsacrificial layer using a self-aligned process. The sacrificial layer isthen removed, and the remaining spacers may then be used to pattern thefins.

In some embodiments, spaces between fin structures 15 are filled with anisolation insulating layer 20, such as shallow trench isolation regions,as shown in FIG. 4.

The isolation insulating layer 20 includes one or more layers of aninsulating material. The insulating material for the insulating layer 20may include silicon oxide, silicon nitride, silicon oxynitride (SiON),SiOCN, fluorine-doped silicate glass (FSG), a low-k dielectric material,or any other suitable dielectric material formed by low pressurechemical vapor deposition (LPCVD), plasma enhanced chemical vapordeposition (PECVD) or flowable CVD. An anneal operation may be performedafter the formation of the isolation insulating layer 20.

In some embodiments, the isolation insulating material extends over theuppermost surface of the fin structures, and a planarization operation,such as a chemical mechanical polishing (CMP) method and/or an etch-backmethod, is subsequently performed to remove the upper portion of theisolation insulating layer 20, as shown in FIG. 4. Further, anadditional etch-back operation or etching operation is performed toreduce the height of the isolation insulating layer 20 as shown in FIG.5. Portions of the fin structures 15 protruding from the isolationinsulating layer 20 will become the channel region of the semiconductordevice, while the portions of the fin structures 15 embedded in theisolation insulating layer 20 will become the well region of thesemiconductor device in certain embodiments.

In some embodiments, a gate stack structure is formed on the finstructures 15, as shown in FIG. 6, a cross-sectional view taken alongline B-B of FIG. 1. The gate stack structure includes a gate dielectriclayer 25 formed on the fin structures 15, a gate electrode layer 30formed on the gate dielectric layer 25, and a hard mask layer 35 formedon the gate electrode layer 30. In some embodiments, the gate stackstructure is a dummy gate stack structure, the gate dielectric layer 25is a dummy gate dielectric layer, and the gate electrode layer 30 is adummy gate electrode layer.

In certain embodiments, the gate dielectric layer 25 includes one ormore layers of a dielectric material, such as silicon oxide, siliconnitride, or high-k dielectric material, other suitable dielectricmaterial, and/or combinations thereof. Examples of high-k dielectricmaterial include HfO₂, HfSiO, HfSiON, HfTaO, HfTiO, HfZrO, zirconiumoxide, aluminum oxide, titanium oxide, hafnium dioxide-alumina(HfO₂—Al₂O₃) alloy, other suitable high-k dielectric materials, and/orcombinations thereof. In some embodiments, the gate dielectric layer 25includes an interfacial layer (not shown) formed between the finstructures 15 and the dielectric material.

The gate dielectric layer 25 may be formed by CVD, atomic layerdeposition (ALD), or any suitable method. The thickness of the gatedielectric layer 25 is in a range from about 1 nm to about 6 nm in someembodiments.

The gate electrode layer 30 is formed on the gate dielectric layer 25.The gate electrode layer 30 includes one or more layers of conductivematerial, such as polysilicon, aluminum, copper, titanium, tantalum,tungsten, cobalt, molybdenum, tantalum nitride, nickel silicide, cobaltsilicide, TiN, WN, TiAl, TiAlN, TaCN, TaC, TaSiN, metal alloys, othersuitable materials, and/or combinations thereof. The gate electrodelayer 30 may be formed by CVD, ALD, electroplating, or other suitablemethod.

In certain embodiments of the present disclosure, one or more workfunction adjustment layers (not shown) are interposed between the gatedielectric layer 25 and the gate electrode 30. The work functionadjustment layers are made of a conductive material such as a singlelayer of TiN, TaN, TaAlC, TiC, TaC, Co, Al, TiAl, HfTi, TiSi, TaSi orTiAlC, or a multilayer of two or more of these materials. For an nFET,one or more of TaN, TaAlC, TiN, TiC, Co, TiAl, HfTi, TiSi and TaSi isused as the work function adjustment layer, and for a pFET, one or moreof TiAlC, Al, TiAl, TaN, TaAlC, TiN, TiC and Co is used as the workfunction adjustment layer. The work function adjustment layer may beformed by ALD, PVD, CVD, e-beam evaporation, or other suitable process.Further, the work function adjustment layer may be formed separately forthe nFET and the pFET, which may use different metal layers.

In some embodiments, when the gate stack is dummy gate stack, the gatedielectric layer 25 is silicon oxide and the gate electrode layer 35 ispolysilicon.

The hard mask layer 35 may include one or more layers of silicon nitrideor silicon oxide in some embodiments, and may be formed CVD, PVD, ALD,or any other suitable technique.

Gate electrode structures 32 are subsequently formed by patterning thegate stack structure, as shown in FIG. 7. The hard mask layer 35 ispatterned using photolithographic and etching techniques, and then thepattern in hard mask is extended through the gate electrode layer 30 andgate dielectric layer 25 exposing the fin structure 15 using anappropriate etching technique, such as anisotropic etching. The gateelectrode structures 32 extend along the second direction (X-direction)substantially perpendicular to the first direction (Y-direction) alongwhich the fin structures 15 extend. The gate electrode structures 32include a gate dielectric layer 25 and a gate electrode layer 30. Thegate electrode structure 32 also includes gate sidewalls 45 (see FIG.10) disposed on opposing sidewalls of the gate electrode 30 and the gatedielectric layer 25, in some embodiments. In some embodiments, the hardmask layer 35 is removed after patterning the gate electrode structures.

In some embodiments, the gate electrode structure 32 has a height H1measured from the top of the fin structure 15 to an uppermost surface ofthe gate electrode layer 32 or hard mask layer 35, as shown in FIG. 7.In certain embodiments the height H1 ranges from 30 nm to 300 nm.

During the course of semiconductor device processing, gate electrodelayer height is decreased as a result of various etching operations,such as a polysilicon patterning operation, for example. As shown inFIG. 8, the gate electrode layer 30 and hard mask layer 35 has a heightH2 measured from the top of the fin structure 15 to the uppermostsurface of the gate electrode layer 30 or hard mask layer 35, whereinheight H2<H1. In some embodiments, H2 ranges from about 30 nm to about290 nm. To increase the height, a silicon oxide layer 40 is subsequentlyselectively formed on the gate electrode structure 32, as shown in FIG.8

According to some embodiments of the present disclosure, a silicon oxidedeposition operation is performed to increase the gate electrodestructure 32 height, thereby forming a silicon oxide layer 40. Incertain embodiments, a height H3 of the silicon oxide layer 40 rangesfrom about 5 nm to about 20 nm. In certain embodiments, (H2+H3)≥H1.

In some embodiments, the gate electrode structure layer 32 height isincreased by depositing silicon dioxide formed by a reaction of asilicon halide and oxygen. In certain embodiments, the silicon halide issilicon tetrachloride and the silicon oxide deposition proceedsaccording to the following formula: SiCl₄+O₂→SiO₂+2Cl₂.

The silicon dioxide layer 40 can be deposited at a number of locationsduring the semiconductor device manufacturing methods. In certainembodiments, the silicon dioxide deposition to increase the level height(interlayer dielectric layer height or gate height) is performed afterpatterning the gate electrode layer, after a metal gate etch back, orafter a self-aligned contact formation.

In some embodiments, the silicon dioxide layer deposition is performedas a plasma deposition at a temperature of ranging from about 55° C. toabout 110° C., and a pressure ranging from about 1.9 mT to about 5 mT. Anitrogen carrier gas having a flow rate of about 100 sccm to about 200sccm is used in certain embodiments. The SiCl₄ and O₂ flow rates rangefrom about 4 sccm to about 16 sccm in some embodiments. In certainembodiments, the SiCl₄ and O₂ flow rates are both about 8 sccm. In someembodiments, the ratio of the SiCl₄ flow rate to the O₂ flow rate rangesfrom about 4/1 to about 1/100.

Silicon dioxide deposited via the oxidation of silicon tetrachlorideaccording to the present disclosure does not form a conformal coating onthe semiconductor device. The silicon dioxide layer 40 is deposited ontop surfaces of the gate electrode 30 or hard mask layer 35, or the topsurfaces of insulating layers, such as the top surfaces of an interlayerdielectric layer rather than on the sidewalls. Further, silicon dioxidedeposited according to the above operation preferentially deposits onsurfaces containing oxygen, such as silicon oxides, as compared todepositing on a silicon surface or a metal surface. Because the oxygenplasma oxidizes silicon and metal surface, some silicon dioxide willalso deposit on the silicon and metal surfaces. The silicon dioxidedeposition according to some embodiments, increases the height of aninterlayer dielectric layer without substantially forming an oxide layerover a silicon or a metal surface. The amount of silicon dioxidedeposited on the silicon or metal surfaces is about 1/10 to about 1/100the amount deposited on an interlayer dielectric layer in someembodiments. In some embodiments, the deposition rate of silicon dioxideon a silicon dioxide surface is about 10 times to about 100 times therate of silicon dioxide deposition on a silicon or metal surface. Thesilicon dioxide will deposit on a nitride surface, such as a siliconnitride surface at a lower rate than the silicon dioxide will deposit onan oxide surface in some embodiments. The deposition rate of silicondioxide on a silicon dioxide surface is about the same as to about 3times greater than that of the rate of deposition on a nitride surfacein some embodiments in some embodiments. However, once a silicon dioxidelayer 40 is formed on the nitride surface, the rate of silicon dioxidedeposition will increase as the later deposited silicon dioxide will bedepositing on an oxide surface rather than a nitride surface. Silicondioxide deposited according to the silicon tetrachloride oxidationoperation preferentially deposits on the uppermost acceptable surfaces(oxide surfaces) as compared to lower surfaces, such as in trenches, andbetween gate structures 32.

In some embodiments, an etchant gas mixture of Cl₂/NF₃ is introducedinto the SiCl₄ and O₂ plasma during deposition of silicon dioxide. Insome embodiments, silicon dioxide deposition, and etching take placesimultaneously. At the upper portions of the device the deposition rateis greater than the etch rate, while at lower portions of the device,such as in trenches between the gates, the etch rate is greater than thesilicon dioxide deposition rate. As a result, the small amount ofsilicon dioxide that is deposited on the lower portions of the device isremoved by the etchant. In some embodiments, the flow rate of Cl₂ rangesfrom 8 sccm to 20 sccm and the flow rate of NF₃ ranges from 10 sccm to20 sccm. In certain embodiments the flow rate of Cl₂ is 13 sccm and theflow rate of NF₃ is 16 scccm. In some embodiments, the ratio of theCl₂/NF₃ flow rates ranges from about 3/1 to about 0 (i.e.—no Cl₂ flow).

FIG. 9 shows a cross sectional view taken along line A-A of FIG. 1 ofthe gate electrode layer 32 and gate dielectric layer 25 wrapping aroundthe fin structures 15, and the hard mask layer 35 and the silicon oxidelayer 40 formed on the gate electrode layer 30.

Adverting to FIG. 10, a view along line B-B of FIG. 1, insulatingsidewall spacers 45 are formed on the side walls of the gate electrodelayers 30, gate dielectric layers 25, hard mask layer 35, and siliconoxide layer 40; and source/drain regions 90 are formed in the finstructures 15 on opposing sides of the gate electrode structures 32. Thesidewall spacers 45 may be formed by suitable deposition and etchtechniques, and may comprise one or more layers of silicon nitride,silicon oxide, silicon carbide, silicon oxynitride, silicon carbonoxynitride, other suitable materials, or combinations thereof.

A blanket layer of a sidewall insulating material may be formed by CVD,PVD, ALD, or other suitable technique. Then, anisotropic etching isperformed on the side-wall insulating material to form a pair ofsidewall insulating layers (spacers) 45 on two main sides of the gateelectrode 30, gate dielectric layer 25, hard mask layer 35, and siliconoxide layer 40. The thickness of the sidewall spacers 45 is in a rangeof about 5 nm to about 30 nm in some embodiments, and in a range ofabout 10 nm to about 20 nm in other embodiments.

Source/drain regions 90 are subsequently formed on opposing sides of thegate electrode structures 32 in some embodiments, as shown in FIG. 10.Source/drain is used in the present disclosure to designate either asource or a drain region. The source/drain regions 90 may be formed byimplanting a dopant into the fin structure 15 in some embodiments. Thedopant is selected from phosphorus, arsenic, antimony, boron, boronfluoride, aluminum, or gallium in some embodiments. The dopant isimplanted in the fin structure at a concentration ranging from 1×10¹⁷ to1×10²¹ atoms/cm³ in some embodiments.

In some embodiments, the portions of the fin structures 15 where thesource/drain regions 90 are to be formed are recessed or etched, and thesource/drain regions 90 are subsequently formed by one or more epitaxyor epitaxial (epi) processes, such that one or more crystalline layersof Si, SiC, SiGe, SiP, SiCP, or Group III-V semiconductor material areformed on the fin structures 15. The crystalline layers are doped with asuitable dopant, as described above. The epitaxy processes include CVDdeposition techniques (e.g., vapor-phase epitaxy (VPE) and/or ultra-highvacuum CVD (UHV-CVD)), molecular beam epitaxy, and/or other suitableprocesses. In other embodiments, the epitaxial source/drain regions 90are formed without forming a recess.

An etch stop layer 95 and an interlayer dielectric layer 50 is formedover the device of FIG. 10, covering the gate electrode structures 32and source/drain regions 90, as shown in FIG. 11. The interlayerdielectric layer 50 has a height H4 measured from the top surface of thefin structure 15. The height H4 ranges from about 80 nm to about 450 nmin some embodiments. In some embodiments, the etch stop layer 95includes one or more layers of insulating material, such as siliconnitride based material including SiN, SiCN, and SiOCN. The etch stoplayer 95 has a layer thickness in a range from about 3 nm to about 15 nmin some embodiments, and is in a range from about 4 nm to about 8 nm inother embodiments. In some embodiments, the interlayer dielectric layer50 is an insulating layer made of an insulating material, such as one ormore layers of silicon oxide, silicon nitride, a low-k dielectricmaterial or a combination thereof. The interlayer dielectric layer 50can be formed by CVD. In certain embodiments, the interlayer dielectriclayer 50 dielectric is a spin on glass (SOG), including phosphosilicateglass (PSG) or borophosphosilicate glass (BPSG).

FIGS. 12 to 15 show cross-sectional views taken along line B-B of FIG. 1of a sequential process for manufacturing a semiconductor deviceaccording to another embodiment of the present disclosure.

In this embodiment, the gate electrode layers 30 and gate dielectriclayers 25 are dummy gate electrode layers and dummy gate dielectriclayers. The interlayer dielectric layer 50 is planarized, and hard masklayer 35 and silicon oxide layer 40, if present, are removed, such as byCMP. The dummy gate electrode layers and dummy gate dielectric layersare subsequently removed by photolithographic and etching operations tocreate gate spaces 55, as shown in FIG. 12.

A high-k gate dielectric layer 60 and metal gate electrode layer 65 aresubsequently formed in the gate spaces 55, as shown in FIG. 13. Examplesof high-k dielectric material for the high-k gate dielectric layer 60include HfO₂, HfSiO, HfSiON, HfTaO, HfTiO, HfZrO, zirconium oxide,aluminum oxide, titanium oxide, hafnium dioxide-alumina (HfO₂—Al₂O₃)alloy, other suitable high-k dielectric materials, or any combinationthereof. In some embodiments, the gate dielectric layer 60 includes aninterfacial layer (not shown) formed between the fin structure 15 andthe gate dielectric layer. The gate dielectric layer 60 may be formed byCVD, ALD, or any suitable method.

The metal gate electrode layer 65 includes one or more layers of ametal, such as aluminum, copper, titanium, tantalum, tungsten, cobalt,molybdenum, tantalum nitride, nickel silicide, cobalt silicide, TiN, WN,TiAl, TiAlN, TaCN, TaC, TaSiN, metal alloys, other suitable materials,or any combination thereof. The metal gate electrode layer 65 may beformed by CVD, ALD, electroplating, or other suitable method.

In certain embodiments of the present disclosure, one or more workfunction adjustment layers (not shown) are interposed between the gatedielectric layer 60 and the gate electrode layer 65. The work functionadjustment layers are made of a conductive material such as a singlelayer of TiN, TaN, TaAlC, TiC, TaC, Co, Al, TiAl, HfTi, TiSi, TaSi,TiAlC, a multilayer of two or more of these materials, or anycombination thereof. The work function adjustment layer may be formed byALD, PVD, CVD, e-beam evaporation, or other suitable method.

In some embodiments, the metal gate electrode layers 65 are subsequentlyrecess etched in a metal gate etch back operation to form recesses 70,as shown in FIG. 14. After the etch back operation, the interlayerdielectric layer 50 has a height H6 measured from the top surface of thefin structure 15 to the uppermost surface of the interlayer dielectriclayer 50. The height H6 of the interlayer dielectric layer 50 rangesfrom about 70 nm to about 300 nm in some embodiments.

In certain embodiments, the silicon dioxide deposition to increase thelevel height (interlayer dielectric layer height) is performed afterpatterning the gate electrode layer, after a metal gate etch back, orafter a self-aligned contact formation. For example, interlayerdielectric layer 50 height can be lost during a metal gate etch backoperation or during a silicon nitride hard mask removal operation aspart of a self-aligned contact formation, so that the height H6 of theinterlayer dielectric layer 50 is less than the height H5 (see FIG. 13)before etch back or hard mask removal operations.

As shown in FIG. 15, the interlayer dielectric layer 50 height isincreased in some embodiments by forming a silicon oxide layer 75 on theinterlayer dielectric layer 50. In certain embodiments, a height H7 ofthe silicon oxide layer 75 ranges from about 5 nm to about 20 nm. Incertain embodiments, (H6+H7)≥H5.

In some embodiments, the interlayer dielectric layer 50 height isincreased by depositing a silicon dioxide layer 75 formed by a reactionof a silicon halide and oxygen. In certain embodiments, the siliconhalide is silicon tetrachloride and the silicon oxide depositionproceeds according to the following formula: SiCl₄+O₂→SiO₂+2Cl₂.

Silicon dioxide deposited via the oxidation of silicon tetrachloridedoes not form a conformal coating on the semiconductor device. Thesilicon dioxide layer 75 is preferentially deposited on top surfaces ofthe interlayer dielectric layer 50 compared to the top of the metal gateelectrodes 65, as shown in FIG. 15. The silicon dioxide depositionaccording to some embodiments, increases the height of the interlayerdielectric layer 50 without substantially forming an oxide layer overthe metal gate electrode 65. The amount of silicon dioxide deposited onthe top of the metal gate electrodes is about 1/10 to about 1/100 theamount deposited on an interlayer dielectric layer in some embodiments.In some embodiments, the deposition rate of silicon dioxide on a silicondioxide surface is about 10 times to about 100 times the rate of silicondioxide deposition on the top of the metal gate electrodes.

FIGS. 16-19 show a cross-sectional views taken along line B-B of FIG. 1of a sequential process for manufacturing a semiconductor deviceaccording to another embodiment of the present disclosure. In someembodiments, a cap insulating layer 80 is formed over the recessed metalgate electrode layers 65 of FIG. 14, as shown in FIG. 16. The capinsulating layer 80 includes one or more layers of insulating materialsuch as silicon nitride based material including SiN, SiCN, and SiOCN.The cap insulating layer 80 may be formed by CVD, physical vapordeposition (PVD) including sputtering, atomic layer deposition (ALD), orother suitable film forming methods. In some embodiments, the capinsulating layer 80 layer is formed over the interlayer dielectric layer50 and a planarization operation, such as an etch-back process and/or achemical mechanical polishing (CMP) process, is performed, therebyobtaining the structure of FIG. 16. The thickness of the cap insulatinglayer 80 is in a range from about 10 nm to about 250 nm in someembodiments, and is in a range from about 15 nm to about 80 nm in otherembodiments. The cap insulating layer 80 is formed as part of a selfaligned contact formation operation in some embodiments.

As shown in FIG. 17, the cap insulating layer 80 is subsequentlyrecessed etch to form a recess 110 in some embodiments. The interlayerdielectric layer 50 may suffer height reduction because of the variousetching operations, providing a height H8, wherein H8<H5. Therefore, theinterlayer dielectric layer 50 height is increased in some embodimentsby forming a silicon oxide layer 85 on the interlayer dielectric layer50. In certain embodiments, a height H9 of the silicon oxide layer 85ranges from about 5 nm to about 20 nm. In certain embodiments,(H8+H9)≥H5.

In some embodiments, the interlayer dielectric layer 50 height isincreased by depositing silicon dioxide formed by a reaction of asilicon halide and oxygen. In certain embodiments, the silicon halide issilicon tetrachloride and the silicon oxide deposition proceedsaccording to the following formula: SiCl₄+O₂→SiO₂+2Cl₂. The silicondioxide will deposit on a nitride surface, such as the cap insulatinglayer 80, at a lower rate than the silicon dioxide will deposit on anoxide surface in some embodiments. The deposition rate of silicon oxideon a silicon oxide surface is about the same as to about 3 times greaterthan that of the rate of deposition on the cap insulating layer 80 insome embodiments.

Adverting to FIG. 18, a second interlayer dielectric layer 115 issubsequently formed over the device of FIG. 17. In some embodiments, thesecond interlayer dielectric layer 115 is an insulating layer made of aninsulating material, such as one or more layers of silicon oxide,silicon nitride, a low-k dielectric material or a combination thereof.The interlayer dielectric layer 115 can be formed by CVD. In certainembodiments, the interlayer dielectric layer 115 dielectric is a spin onglass (SOG), including phosphosilicate glass (PSG) orborophosphosilicate glass (BPSG).

In some embodiments, vias are subsequently formed in the interlayerdielectric layers 50, 115 by using suitable photolithographic andetching operations. Using suitable material deposition techniques,source/drain contacts 120 are formed in some vias providing electriccontact to the source/drain regions 90, and gate electrode contacts 125are formed in some vias providing electrical contact to the gateelectrode layers 65, as shown in FIG. 19. In some embodiments, a contactbarrier liner layer (not shown) is formed in the vias prior to formingthe contacts 120, 125. In some embodiments, the contact barrier linerlayer is formed of a metal nitride, such as TaN or TiN. The contactbarrier liner layer may be formed by ALD, PVD, CVD, or other suitableprocess. In some embodiments, the contacts 120, 125 are formed ofaluminum, copper, titanium, tantalum, tungsten, cobalt, molybdenum,nickel, alloys thereof, and other suitable conductive materials. Thecontacts 120, 125 may be formed by CVD, ALD, electroplating, or othersuitable methods.

It is understood that the semiconductor devices undergo furtherfabrication processes to form various features such as contacts/vias,interconnect metal layers, dielectric layers, passivation layers, etc.Additional operations performed on the semiconductor device may includephotolithography, etching, chemical-mechanical polishing, thermaltreatments, including rapid thermal annealing, depositions, doping,including ion-implantation, photoresist ashing, and liquid solventcleaning.

The present disclosure provides a method to increase gate electrodestructure or interlayer dielectric layer height. Certain semiconductorprocessing operations, such as patterning of a gate electrode layer,metal gate etch back, and self-aligned contact formation can result in aloss of gate electrode or interlayer dielectric. In certain embodiments,the silicon dioxide deposition to increase the level height (interlayerdielectric layer height or gate height) is performed after patterningthe gate electrode layer, after a metal gate etch back, or after aself-aligned contact formation to restore the original heights of thegate electrode or interlayer dielectric layer, and thereby increase theyield of the semiconductor manufacturing process.

The present disclosure helps prevent polysilicon collapse of high aspectratio gate electrodes. The present disclosure also eliminates the needfor a surface modification technique using a surfactant to preventpolysilicon collapse of high aspect ratio gate electrodes, and theresultant need to remove the surfactant after the surface modificationtechnique.

It will be understood that not all advantages have been necessarilydiscussed herein, no particular advantage is required for allembodiments or examples, and other embodiments or examples may offerdifferent advantages.

An embodiment of the present disclosure is a method for fabricating asemiconductor device, including forming a gate electrode structure overa first region of a semiconductor substrate, and selectively forming anoxide layer overlying the gate electrode structure by reacting a halidecompound with oxygen to increase a height of the gate electrodestructure. In an embodiment, the halide compound is silicontetrachloride. In an embodiment, the oxide layer is silicon dioxide. Inan embodiment, a height of the oxide layer overlying the gate electrodestructure is about 5 nm to about 20 nm. In an embodiment, before formingthe gate electrode structure, the method includes patterning thesubstrate to form a fin extending in a first direction, and forming thegate electrode structure overlying the fin and extending in a seconddirection substantially perpendicular to the first direction. In anembodiment, the method includes forming source/drain regions on secondregions of the semiconductor substrate, wherein the second regions ofthe semiconductor substrate are on opposing sides of the gate electrodestructure. In an embodiment, the forming the gate electrode structureincludes forming a gate dielectric layer overlying the substrate,forming a gate electrode layer overlying the gate dielectric layer,forming a hard mask layer overlying the gate electrode layer, patterningthe hard mask layer to form a patterned hard mask, and removing portionsof the gate electrode layer and gate dielectric layer not covered by thehard mask. In an embodiment, the oxide layer is formed overlying thehard mask.

Another embodiment of the present disclosure is a method for fabricatinga semiconductor device, including forming a dummy gate electrodestructure over a region of a semiconductor substrate. An insulatinglayer is formed over the dummy gate electrode structure, and the dummygate electrode structure is removed. A gate electrode structure isformed over the region of the semiconductor substrate where the dummygate electrode structure was removed. An oxide layer is formed overlyingthe insulating layer by reacting a halide compound with oxygen toincrease a height of the insulating layer without substantially formingan oxide layer over the gate electrode structure. In an embodiment, thehalide compound is silicon tetrachloride. In an embodiment, the oxidelayer is silicon dioxide. In an embodiment, a height of the oxide layeroverlying the insulating layer is about 5 nm to about 20 nm. In anembodiment, the gate electrode structure includes a high k gatedielectric layer and a metal gate electrode formed over the high k gatedielectric layer. In an embodiment, the method includes performing anetch back of the metal gate electrode before forming the oxide layer onthe insulating layer.

Another embodiment of the present disclosure is a method for fabricatinga semiconductor device, including forming a dummy gate electrodestructure over a region of a semiconductor substrate. A first insulatinglayer is formed over the dummy gate electrode structure, and the dummygate electrode structure is removed. A gate electrode structure isformed over the region of the semiconductor substrate where the dummygate electrode structure was removed. A second insulating layer isformed over the gate electrode structure. An oxide layer is formedoverlying the first insulating layer by reacting a halide compound withoxygen to increase a height of the insulating layer withoutsubstantially forming an oxide layer over the second insulating layer. Avia is formed in the first insulating layer and the second insulatinglayer exposing the gate electrode structure. A conductive material isdeposited in the via to form gate electrode contacts. In an embodiment,the halide compound is silicon tetrachloride. In an embodiment, theoxide layer is silicon dioxide. In an embodiment, the gate electrodestructure includes a high k gate dielectric layer and a metal gateelectrode formed over the high k gate dielectric layer. In anembodiment, the method includes recessing the metal gate electrodebefore forming the second insulating layer on the gate electrodestructure. In an embodiment, the second insulating layer is a nitridelayer.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A method for fabricating a semiconductor device,comprising: forming a gate electrode structure over a first region of asemiconductor substrate; selectively forming an oxide layer overlyingthe gate electrode structure by reacting a halide compound with oxygento increase a height of the gate electrode structure.
 2. The methodaccording to claim 1, wherein the halide compound is silicontetrachloride.
 3. The method according to claim 1, wherein the oxidelayer is silicon dioxide.
 4. The method according to claim 1, wherein aheight of the oxide layer overlying the gate electrode structure isabout 5 nm to about 20 nm.
 5. The method according to claim 1, furthercomprising before forming the gate electrode structure: patterning thesubstrate to form a fin extending in a first direction; and forming thegate electrode structure overlying the fin and extending in a seconddirection substantially perpendicular to the first direction.
 6. Themethod according to claim 1, further comprising forming source/drainregions on second regions of the semiconductor substrate, wherein thesecond regions of the semiconductor substrate are on opposing sides ofthe gate electrode structure.
 7. The method according to claim 1,wherein the forming the gate electrode structure comprises: forming agate dielectric layer overlying the substrate; forming a gate electrodelayer overlying the gate dielectric layer; forming a hard mask layeroverlying the gate electrode layer; patterning the hard mask layer toform a patterned hard mask; and removing portions of the gate electrodelayer and gate dielectric layer not covered by the hard mask.
 8. Themethod according to claim 7, wherein the oxide layer is formed overlyingthe hard mask.
 9. A method for fabricating a semiconductor device,comprising: forming a dummy gate electrode structure over a region of asemiconductor substrate; forming an insulating layer over the dummy gateelectrode structure; removing the dummy gate electrode structure;forming a gate electrode structure over the region of the semiconductorsubstrate where the dummy gate electrode structure was removed; andforming an oxide layer overlying the insulating layer by reacting ahalide compound with oxygen to increase a height of the insulating layerwithout substantially forming an oxide layer over the gate electrodestructure.
 10. The method according to claim 9, wherein the halidecompound is silicon tetrachloride.
 11. The method according to claim 9,wherein the oxide layer is silicon dioxide.
 12. The method according toclaim 9, wherein a height of the oxide layer overlying the insulatinglayer is about 5 nm to about 20 nm.
 13. The method according to claim 9,wherein the gate electrode structure comprises a high k gate dielectriclayer and a metal gate electrode formed over the high k gate dielectriclayer.
 14. The method according to claim 13, further comprisingperforming an etch back of the metal gate electrode before forming theoxide layer on the insulating layer.
 15. A method for fabricating asemiconductor device, comprising: forming a dummy gate electrodestructure over a region of a semiconductor substrate; forming a firstinsulating layer over the dummy gate electrode structure; removing thedummy gate electrode structure; forming a gate electrode structure overthe region of the semiconductor substrate where the dummy gate electrodestructure was removed; forming a second insulating layer over the gateelectrode structure; forming an oxide layer overlying the firstinsulating layer by reacting a halide compound with oxygen to increase aheight of the insulating layer without substantially forming an oxidelayer over the second insulating layer; forming a via in the firstinsulating layer and second insulating layer exposing the gate electrodestructure; and depositing a conductive material in the via to form agate electrode contact.
 16. The method according to claim 15, whereinthe halide compound is silicon tetrachloride.
 17. The method accordingto claim 15, wherein the oxide layer is silicon dioxide.
 18. The methodaccording to claim 15, wherein the gate electrode structure comprises ahigh k gate dielectric layer and a metal gate electrode formed over thehigh k gate dielectric layer.
 19. The method according to claim 18,further comprising recessing the metal gate electrode before forming thesecond insulating layer on the gate electrode structure.
 20. The methodaccording to claim 15, wherein the second insulating layer is a nitridelayer.